Given, the equation of translated parabola x2+13=4y+6x.
On reaaranging we get,
⇒x2−6x+9=4y−4
⇒(x−3)2=4(y−1)
So, the vertex of this parabola is (3,1) and a=1.
Now, the equation of directrix of translated parabola is give by y=k−a i.e. y=1−1=0.
Hence, the equation of directrix for the given translated parabola is y=0.